Assertion : Staggered conformation of ethane is `12.5 kJ mol^(−1)`
more stable than the eclipsed conformation.
Reason : The two conformations of ethane cannot be separated at room temperature.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To solve the question, we need to analyze the assertion and reason provided about the conformations of ethane.

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that the staggered conformation of ethane is 12.5 kJ/mol more stable than the eclipsed conformation.
- **Explanation**: In ethane, the staggered conformation has the hydrogen atoms positioned as far apart as possible, minimizing repulsion between them. This results in lower potential energy compared to the eclipsed conformation, where the hydrogen atoms are closer together, leading to increased repulsion and higher energy.

2. **Understanding the Reason**: The reason states that the two conformations of ethane cannot be separated at room temperature.
- **Explanation**: At room temperature, the energy barrier (12.5 kJ/mol) between the staggered and eclipsed conformations is not large enough to prevent the interconversion between these two forms. The molecules have enough kinetic energy to overcome this barrier, allowing them to rotate around the C-C single bond and switch between conformations.

3. **Conclusion**: Both the assertion and reason are true. However, the reason does not correctly explain the assertion. The assertion is about the stability difference between the two conformations, while the reason discusses their interconversion at room temperature.

### Final Answer:
- Both the assertion and reason are true, but the reason is not the correct explanation for the assertion.